Project Description
Short Version:
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We need an experienced hardware engineer to design a custom ESP32-S3 based industrial controller PCB with Ethernet, opto-isolated outputs, protected digital inputs, RS232/RS485 and a separate 2.9" e-paper display unit.
The system consists of two parts: a remote e-paper display in a small enclosure, and a main controller/I/O box mounted inside a machine cabinet. The display must connect to the controller by cable.
The software will be developed by us. This project is only for hardware, PCB and enclosure design.
Required deliverables: KiCad schematic, PCB layout, Gerbers, BOM, pick-and-place files, STEP model, STL/STEP enclosure files, connector pinout and wiring documentation.
Required experience: ESP32-S3, W5500 Ethernet, e-paper displays, 12V/24V industrial power design, opto-isolated outputs, protected digital inputs, RS232/RS485, KiCad and enclosure design.
Full project description:
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We are looking for an experienced electronics hardware engineer and enclosure designer to design a custom embedded controller PCB and matching enclosures.
The project consists of two separate hardware parts:
1. Remote display unit
A compact e-paper display module in a small enclosure or panel-mount frame.
The display will be mounted separately from the main controller.
2. Main controller / I/O box
A separate PCB and enclosure that will be mounted inside a machine cabinet.
This box will contain the ESP32 controller, Ethernet, power supply, opto-isolated outputs, digital inputs and communication interfaces.
The software will be developed by us.
This project is only for the hardware design, PCB layout and mechanical enclosure design.
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Main goal
Design a production-ready custom PCB and enclosure for an industrial embedded controller based on:
• ESP32-S3 or equivalent ESP32 module
• Ethernet RJ45 connection
• 2.9 inch e-paper display connection
• Opto-isolated transistor outputs
• Protected digital inputs
• RS232 / RS485 communication
• 12V / 24V DC industrial power input
• Separate display enclosure
• Separate controller / I/O box enclosure
The device will be used in small machine-control environments.
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Functional requirements
1. Remote display unit
The display unit must:
• Use a 2.9 inch black/white e-paper display
• Preferably be compatible with common Waveshare / Good Display type panels
• Use SPI or another suitable interface
• Be mounted separately from the main PCB
• Be placed in a compact and professional-looking enclosure
• Be suitable for panel mounting or surface mounting
• Connect to the main controller using a reliable cable and connector
• Be serviceable and replaceable
• Have a clean front-facing appearance
The display does not need touch functionality.
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2. Main controller PCB
The main PCB must include:
• ESP32-S3 module or equivalent ESP32 module
• Ethernet RJ45 connection
• W5500 Ethernet controller or suitable alternative
• 12V / 24V DC power input
• Protected power input stage:
o reverse polarity protection
• DC/DC power conversion to required voltages
• 4 to 8 opto-isolated outputs expandable with 16 outputs via SPI
• 2 protected digital inputs
• 1 RS485 interface
• 1 RS232 interface
• Connector for the remote e-paper display
• Programming/debug connector
• Reset/Boot button
• Status LEDs
• Industrial screw terminals or pluggable terminal blocks
Optional but preferred:
• DIN-rail mountable enclosure or DIN-rail adapter
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I/O requirements
Initial target configuration:
• 4-8 opto-isolated outputs expandable with extra 16 outputs board
• 2 protected digital inputs
• 1 RS485 port
• 1 RS232 port
• 1 Ethernet RJ45 port
• 1 remote display connector
• 1 power input connector, 12V - 24V DC
• Status LEDs for:
o power
o Ethernet
o ESP32 status
o output activity
o communication activity if useful
The freelancer may propose improvements to the I/O design.
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Opto-output requirements
The outputs should be designed as industrial low-power control outputs, not mechanical relays.
Preferred output concept:
• Opto-isolated outputs
• Open collector or open drain style output
• Suitable for switching external low current 12V / 24V DC control signals
• Clearly specified maximum current per output
• Terminal blocks for field wiring
• LED indication per output preferred
The freelancer may propose the most suitable output topology.
Possible options:
• Optocoupler + transistor/MOSFET output
• Photovoltaic MOSFET driver + MOSFET
• Solid-state relay output
• Opto-MOS output
The final choice should be cost-effective, reliable and easy to source.
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Display requirements
Target display:
• 2.9 inch e-paper
• Black/white
• Approximately 296 × 128 pixels
• SPI interface preferred
• Low power
• Good readability in daylight
• Suitable for displaying simple graphics and text
The display must be connected to the main controller through a practical cable solution. The cable should be robust enough for internal machine installation.
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Mechanical requirements
We need two separate mechanical designs.
Display enclosure
The display enclosure must:
• Hold the 2.9" e-paper display securely
• Have a clean front appearance
• Allow panel mounting or surface mounting
• Protect the display and electronics
• Include cable exit or cable connector
• Be compact and not too expensive to produce
• Be suitable for 3D printing during prototyping
• Be designed with future small-series production in mind
Main controller enclosure
The controller enclosure must:
• Hold the main PCB securely
• Be suitable for mounting inside a machine cabinet
• Preferably support DIN-rail mounting or screw mounting
• Provide access to:
o power input
o opto-isolated outputs
o digital inputs
o RS232 / RS485
o Ethernet RJ45
o display connector
• Be practical for wiring and service
• Look professional
• Be suitable for 3D printing or small-series production
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Electrical design requirements
The design must be robust enough for industrial use.
Important requirements:
• Stable 12V / 24V DC input design
• Protection against reverse polarity
• Surge and ESD protection where appropriate
• Good grounding strategy
• Proper opto-isolated output design
• Correct Ethernet layout and magnetics/RJ45 design
• Correct SPI/display connector routing
• Clear silkscreen labels on all connectors
• Service-friendly layout
• Avoid hard-to-source or obsolete components
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Required deliverables
The freelancer must deliver:
1. Complete schematic
o KiCad preferred
o All parts fully defined
o No placeholder components
2. PCB layout
o Production-ready
o Proper routing for Ethernet, power and I/O
o Correct connector placement
o Clear silkscreen
3. Manufacturing files
o Gerber files
o Drill files
o Pick-and-place files
o BOM
4. 3D files
o STEP model of the PCB
o STEP files for both enclosures
o STL files for prototype printing
5. Documentation
o Connector pinout
o Wiring diagram
o Display cable pinout
o Power input description
o Output description
o Digital input description
o RS232 / RS485 pinout
o Assembly notes
6. Source files
o Full KiCad project
o Full mechanical CAD source files where possible
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Required experience
The freelancer should have experience with:
• ESP32 / ESP32-S3 hardware design
• Ethernet hardware design, preferably W5500
• E-paper display hardware integration
• SPI display connections
• 12V / 24V industrial power supply design
• Opto-isolated output circuits
• Opto-isolated or protected digital input circuits
• RS232 interface design
• RS485 interface design
• ESD and surge protection
• KiCad PCB design
• Mechanical enclosure design
• STEP / STL generation
• Designing hardware for real-world industrial environments
Experience with DIN-rail modules, machine control, industrial automation or embedded controllers is a plus.
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Preferred component direction
We are considering the following architecture, but the freelancer may propose improvements:
• ESP32-S3 module
• W5500 Ethernet controller
• 2.9" SPI e-paper display
• 12V / 24V input
• Buck converter to 5V
• 3.3V regulator for ESP32 and logic
• Optocoupler or Opto-MOS outputs
• Opto-isolated inputs
• MAX3485 or similar RS485 transceiver
• MAX3232 or similar RS232 transceiver
• Pluggable terminal blocks for field wiring
• Internal connector for remote display cable
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Suggested milestones
Milestone 1 — Architecture and component selection
• Review requirements
• Create block diagram
• Select main components
• Define connectors
• Define display cable concept
• Define enclosure concept
Milestone 2 — Schematic design
• Complete schematic
• Power input and protection
• ESP32 section
• Ethernet section
• Opto-isolated outputs
• Digital inputs
• RS232 / RS485
• Display connector
Milestone 3 — PCB layout
• Complete PCB routing
• 3D PCB preview
• Design review
• Manufacturing output files
Milestone 4 — Mechanical design
• Display enclosure
• Main controller enclosure
• Mounting details
• Cable entries
• STEP/STL files
Milestone 5 — Final delivery
• KiCad source files
• Gerbers
• BOM
• Pick-and-place files
• STEP files
• STL files
• Pinout documentation
• Assembly documentation